Production of spun yarns



Patented Jan. 8, 1952 PRODUCTION OF SPUN YARNS William Whitehead, ForestHills N. Y., and John B. Steiding, Midland, and Leo B. Brown and WilliamL. Rooney, Cumberland, Md., assignors to Celanese Corporation ofAmerica, a corporation of Delaware Application November 5, 1948, SerialNo. 58,432

l7 Claims.

This invention relates to textiles, and relates more particularly to aprocess for producing staple fibers, rovings and spun yarns.

As is well known, continuous filaments of regenerated celluloseexhibiting an exceptionally high-tenacity and dimensional stability maybe produced by thesaponification of stretched filaments having a basisof an organic acid ester of cellulose. If the continuous high-tenacityregenerated cellulose filaments produced in this manner are converted tofibers of staple length, they may be employed for the production of spunyarns which find extensive application wherever yarns of unusually highstrength and dimensional stability are desired. However, themanufacturing cost of these yarns has been high since the processeshitherto proposed for their production have been relatively complex.

It is an important object of this invention to provide a process forproducing spun yarns of high-tenacity regenerated cellulose staplefibers which will overcome the foregoing and other disadvantages of theprior processes, and which will be especially simple and efficient inoperation.

A further object of this invention is the provision of a process forproducing high-tenacity regenerated cellulose staple fibers, rovings andspun yarns, in which a tow of continuous filaments having a basis of anorganic acid ester of cellulose is stretched while the filaments are ina plasticized or softened state, the tow of stretched filaments isconverted to a roving by breaker-drafting and twisting operations, andthe roving is then saponified and spun into yarn.

Other objects of this invention, together with certain details ofconstruction, will be apparent from the followin detailed descriptionand claims.

In carrying out the process of our invention, we form a bundle or tow ofa plurality of continuous filaments having a basis of an organic acidester of cellulose. Thereafter, all of the filaments in the tow areplasticized or softened and the tow is stretched while the'filaments arein the plasticized or softenedstate. The filaments of the tow arerestored to their unplasticized state and the tow is converted to asliver by breaker-drafting which reduces the continuous filaments tofibers of staple length. A twist is then imparted to the sliver toconvert the same into a roving. The staple fibers making up this rovingare saponified by treatment of the roving with saponifying agents and,after washing and drying, the roving is spun into a yarn. By carryingout the production of spun yarns of hightenacity regenerated cellulosestaple fibers in accordance with this process, many of the stepshitherto deemed necessary in the production of said yarns are completelyeliminated, and the manufacturing cost of the yarns is thereby reatlyreduced.

The continuous filaments which are employed into a tow directly as theyleave the spinning cabinets in which they are formed, or the tow may beproduced by assembling the filaments from a plurality of packages onwhich they have been previously wound. Any desired number of filamentsbetween about and 15,000 may go to form the tow. The denier of each ofthe filaments may vary between about 2 and 40 and the total denier ofthe tow may vary between about 10,000 and 150,000. The number offilaments, the denier of the individual filaments and the total denierof the tow will depend largely upon the results desired and upon themanner in which the process is carried out. After being formed, the towmay be passed directly to the next stage of the process, but it is firstpreferably wound onto a support, coiled into a can, or otherwisesuitably packaged.

After the tow has been formed, all of the filaments in the tow must beplasticized before the tow is stretched. Any of a number of expedlentsmay be employed, either alone or in combination, to effect thisplasticization. For example, the tow may be subjected to the action ofvarious solvents or softening materials such as dioxan, diacetonealcohol, diethylene glycol diacetate or glycerol formal. In general,however, it is preferred to plasticize the filaments by subjecting themto the action of steam or hot water having a temperature between about100 and C., since steam and hot water are less expensive than otherplasticizing agents. In addition, filaments plasticized with steam orhot water may be returned to an unplasticized state simply by permittingthem to cool, whereas in returning filaments plasticized with othermaterials to the unplasticized state, they must be subjected to specialtreatments such as washing to remove the plastlcizing agents therefrom.

effect a certain draft of the sliver.

The tow of continuous, plasticized filaments is subjected to astretching operation during which the individual filaments are elongatedfrom about 150 to 2000% based on their original length. If desired, theplasticizing' and stretching .of the tow may be carried outsimultaneously by passing the tow through a chamber to which theplasticizing agent is admitted, and applying sufficient stress to thetow to obtain the required elongation of the filaments. After thestretching operation is com leted, the filaments in the tow are restoredto an unplasticized state by removing the solvent or softening agentstherefrom or, when water or steam have been em loyed as the plasticizinga ents, by cooling the filaments. As a result of the stretchingoperation the total denier of the tow will be reduced to between about1,000 and 15,000. The tow of stretched filaments may be passed directlyand continuously to the nexto eration or it may be packaged in anysuitable manner.

The stretched filaments have a low extensibility as a result ofwhichthey will exhibit only a small elongation when subjected to stress. Inaddition, the stretched filaments have a good elastic memory so thatthey may be stressed even to their breaking point, and the fibersproduced by breaking will return to their original length and willregain their original physical properties rapidly.

One or preferably several tows containing the stretched filaments arenext passed to a set of breaker-draft rollers operating at a draft ratiobetween about 1.5 and 3.0, or more, which will break all of thecontinuous filaments into individual fibers of staple length therebyconverting the tow into a sliver. In addition to breaking the filaments,the breaker-draft rollers will also The length of the staple fibers,which preferably ranges from about 3 to 8 inches, will depend upon thespacing between the breaker-draft rollers, being about one or two inchesle s than said spacing. Owing v to the low extensibility of thestretched filaments,

only a low draft ratio is needed to insure the breakin of all thefilaments into fibers of staple length. Moreover, as a result of thegood elastic memory of the stretched filaments, the fibers producedtherefrom will have physical properties very similar to those of thecontinuous filaments. This is in sharp contrast to the behaviour ofother filamentary materials whose physical properties are permanentlyaltered by being stressed to their breaking point. Although all of thecontinuous filaments are broken into fibers of staple length during thedrafting operation, the sliver itself retains its continuity since thefilament breaks are distributed unevenly therethrough.

After the sliver leaves the breaker-draft rollers it has a twistimparted thereto producing a roving, the twist preventing the separationof the individual fibers during the subsequent liquid treatments of saidroving. The twist should not be lower than about 0.25 turn per inch norhigher than about 1 turn per inch, since a lower degree of twist willpermit the individual staple fibers to separate from the roving and ahigher degree of twist will hinder the penetration of treating solutionsinto the roving thereby unduly lengthening the time of treatment. Thenecessary twist may be imparted to the sliver in any desired manner. Forexample, the sliver may be passed to a fly frame, a cap frame, or a ringframe which will simultaneously draft the sliver, impart the requirednumber of turns per inch thereto, and wind the resultant roving onto abobbin or other suitable package.

The roving may then be saponified' either continuously orintermittently. The packages of roving may, for example, be immersedinto a saponification bath for a sufllcient period of time to effect thecomplete saponification of the fibers. Or, if desired, the roving may berewound into larger packages ranging up to 6, or more pounds in weightbefore saponification. Alternatively, a saponification bath may beapplied to the roving as it is drawn from the package on which it hasbeen wound or directly as it leaves the twisting apparatus in which itis formed. During the saponification treatment the staple fibersdecrease by approximately 39% in cross-sectional area. As a result ofthis decrease in cross-sectional area there is a. strong tendency forthe staple fibers to separate from the roving and to snarl and mat. Byhaving a minimum of 0.25 turn per inch in the roving before thesaponification solution is applied thereto, this tendency for the staplefibers to snarl and mat is completely eliminated. When thesaponification is complete, the roving may be washed to remove theresidual saponification solution and the salts formed during thesaponification therefrom, after which the roving is dried and is readyto be spun into yarn.

The saponification of the staple fibers in the roving may be carried outwith any desired type of saponifying bath. Among the baths which aresuitable for this purpose are solutions of alkaline materials such assodium hydroxide, sodium carbonate, or ammonium hydroxide. Mixtures ofsuch alkaline materials and buffering agents including sodium acetate,sodium citrate, or sodium sulfate may also be employed. If desired, thesaponifying bath may be maintained at elevated temperatures to increasethe rapidity with which it acts.

It has been found that during the saponification, washing and dryingsteps there is an initial increase followed by a subsequent decrease inthe length of the roving. Immediately after the saponification solutionis applied, there is a rapid increase in the length of the roving whichis followed by a slight shrinkage during the remainder of thesaponification period. The rate of shrinkage increases during thesubsequent washing and drying steps. If the saponification, washing anddrying are carried out continuously as the roving passes from one pointto another, provision must be made to prevent an excessive amount ofslack from developing in the roving as its length in creases and toprevent excessive tensions from being built up in the roving as itshrinks. One manner in which compensation may be made for both theinitial increase in the length of the roving and its subsequentshrinkage, is to carry out the treatments of the rovin as it passes overtwo spaced rollers, having diameters which vary along the lengththereof. By having the diameter of the rollers increase sharply at theirfeed end, decrease slightly in the portion of the rollers adjacent thefeed end and decrease more rapidly at their discharge end, there will beno opportunity for either excessive slack or excessive tensions todevelop in the roving.

After the saponification, washing and drying steps have been completed,one, or a number of rovings may be spun in conventional manner toproduce a yarn of any desired denier. The yarn produced in this mannerexhibits a. tenacity ranging up to 4 or 5, or more, grams per denier andalso has an exceptionally good dimensional stability. It may be employedeither alone or inan apparatus for plasticizing and stretching a tow ofcontinuous filaments,

Fig. 2 is a diagrammatic view of an apparatus for breaker-drafting andtwisting a tow of continuous filaments to convert the same into aroving, and

Fig. 3 is a diagrammatic view of an apparatus for continuouslysaponifying, washing and drying a roving of staple fibers having a basisof an organic acid ester of cellulose.

Like reference numerals indicate like parts throughout the several viewsof the drawing.

Referring now to the drawing, the reference numeral II designates a towof continuous filaments which is plasticized and stretched while passingthrough a chamber indicated generally by the reference numeral I2. Thechamber I2 is defined by a lower wall I3, upper walls I4 and I6, and endwalls I1 and I8. Partitions I9, 2|

and 22 divide the chamber I2 into four compartments 23, 24, 26 and 21through which the tow II passes in succession. The tow II enterscompartment 23 through an aperture 28 in the end wall I1, passes aroundpulleys 29, 3| and 32, which are positively driven by any suitable means(not shown), and leaves said compartment through an aperture 33 in thepartition I9. The tow I I then traverses compartments 24, 26 and 21,passing through apertures 34, 36, and 31 in the partitions 2| and 22 andin the end wall I6, respectively. The clearance between the tow II andthe apertures through which it passes is preferably kept at a minimum,consistent with the free movement of the tow, to limit leakage oi theplasticizing agent through said apertures. Since the stretched tow has asmaller diameter than the unstretched tow, the apertures 36 and 31 mustbe of smaller cross-sectional area than the apertures 28, 33 and 34 tomaintain this minimum clearance. After leaving the chamber I2, the towII is wrapped several times around a wheel 38 which is positively drivenby any suitable means (not shown).

A plasticizing agent such as steam under pressure is admitted into thecompartment 26 through a pipe 39 and, after acting to plasticize thefilaments in the tow II, leaves said compartment through a second pipe4I The steam in the compartment 26 tends to escape past the tow IIthrough the apertures 34 and 36 exerting a strong stretching force onthe plasticized tow 'II. If this fiow of steam were permitted to proceedunchecked it would break the filaments in said tow. To limit the flow ofsteam through the aperture 34, cold water under a pressure only slightlyless than the pressure of the steam is forced into the compartment 23through a pipe 42. The water flows from the compartment 23 through theaperture 33 past the tow II into the, compartment 24. The pressure ofthe water in the compartment 24 limits the fiow of steam through theaperture 34 thereby limiting the stretching force exerted by said fiowof steam on the tow II. What steam does enter the compartment 24 iscondensed by the water therein, and leaves said compartment togetherwith the water through a pipe 43. While the water in the compartment 23flows past the tow II through the aperture 26 exerting an endwise forceon the tow, this force is not objectionable since it is not transmittedpast the pulleys 28, 3| and 32 and is therefore restricted to theunplasticized tow.

Similarly, to limit the flow of steam through the aperture 36, coldwater under a pressure less than the pressure of the steam in thecompartment 26 is forced into the compartment 21 through a pipe 44. Thesteam entering the compartment 21 is condensed by the water in saidcompartment and leaves the compartment to gether with the water througha pipe 46. The water in the compartment 21, in addition to controllingthe rate of flow of steam through the aperture 36, also serves to coolthe tow and restore it to its unplasticized state. By regulating thedifference in pressure between the steam in compartment 26 and the waterin compartment 21, the rate of fiow of steam through the aperture 36 maybe controlled, thereby regulating the endwise force resulting from saidflow on the tow. An additional endwise force is exerted on the tow I Iby the flow of water from the compartment 21 past the tow I I throughthe aperture 31. The tow II is drawn from the chamber I2 by means of thewheel 36 which rotates at a higher peripheral speed than the pulleys 29,3I and 32. The cumulative effect of the endwise forces exerted on thetow II by the flow of steam through the aperture 36, the flow of waterthrough the aperture 31 and the rotation of the wheel 36 acts to impartthe desired stretch to said tow. By varying the peripheral speed of thewheel 36, with or without changing the pressures in the several compartments of the chamber I2, the degree of stretching of tow I I may bevaried over a wide range.

After the tow II has been stretched and restored to its unplasticizedstate, it is passed to a first set of breaker-draft rollers 41, 48 and49 which are positively driven at a given peripheral speed by anysuitable means (not shown). Any of these three rolls may have a rigidedge embedded therein for the purpose of weakening the tow at spacedpoints. The tow II then passes to a second set of breaker-draft rollers5| and 5 2 which are positively driven by any suitable means (not shown)at a higher peripheral speed than that of the first set of breaker-draftrollers. The difference in the peripheral speeds of the first and secondset of breaker-draft rollers breaks the continuous filaments in the towto fibers of staple length, produces a sliver 53 and also drafts thesliver thereby reducing its denier. The staple fibers are from one totwo inches shorter than the spacing between the first and second set ofbreaker-draft rollers, and by varying said spacing it is possible tocontrol the lengthof the staple fibers in the sliver 53.

From the breaker-draft rollers, the sliver 53 passes to a slubber,intermediate or fiy-frame, indicated generally by the reference numeral54, which draws the sliver and imparts a twist thereto, converting thesame into a roving 56 and winds said roving onto a bobbin 51. Theflyframe 54 comprises a flyer 58 which rotates about a shaft 59, and anarm 6| which is traversed by any suitable means (not shown) to wind theroving 66 onto the bobbin 51 The roving 56, after being unwound from thebobbin 61, is passed over a pulley 62 to a set of positively-drivenhollow rollers 63 upon which it is saponified, washed and finally driedin a continuous manner. At their feed end 64, the diameter of therollers 63 increases rapidly to take up 7 the slack which develops inthe roving immediately after the saponifying solution is appliedthereto. Next adjacent the feed end 64, the diameter of the rollers 63decreases slightly as at 66 to accommodate the slight shrinkage whichtakes place in the roving 56 as the saponifying agent continues to actthereon. Finally, at their discharge end 61, the diameter of the rollers63 decreases more rapidly to accommodate the shrinkage of the roving 56during the washing and drying steps.

Positioned above the rollers 63, is a header 68 provided with aplurality of jets 69 through which the saponifying bath is applied 'tothe roving 56. Adjacent the header 68, is a second header 1|, similarlyprovided with a plurality of jets 12 by means of which wash water isapplied to the roving 56 to wash away the residue of the saponifyingsolution. After acting on the roving, the saponifying bath.'and washwater are collected in a pan 13, from which they may be removed througha drain 14. The saponified and washed roving is then dried as it passesover the heated end of each of the rollers 63. To effect this heating, acompartment 16 is formed in each of the rollers 63 by means ofinternally positioned walls 11. Steam or other suitable heating mediumis admitted into the compartments 16 through pipes 16, which also act asbearings upon which the rollers 63 are journalled. The condensate whichis formed in the compartments (6 is discharged therefrom through pipes19 which are positioned concentrically of the pipes 18. After beingdried, the roving 56 passes from the rollers 63 over a pulley 8|, andmay be packaged or led directly to a spinning frame for conversion intoyarn.

The following example is given to illustrate this invention:

Example A tow of 1,440 cellulose acetate filaments having a total denierof about 15,552 is entered into the chamber l2. Saturated steam at apressure of about 45 pounds per square inch above atmospheric and atemperature of about 130 C. is admitted into the compartment 26 and actsto plasticize the filaments in the tow as it passes therethrough.Simultaneously, water at room temperature of about C. is forced into thecompartment 23 at a pressure of about 38 pounds per square inch aboveatmospheric to limit the flow of steam through the aperture 34. Water atroom temperature of about 25 C. is also forced into the compartment 21at a pressure of about 8 pounds per square inch above atmospheric tocontrol the flow of steam through the aperture 36. After leaving thechamber 12 the tow passes around the wheel 38 which is driven at apcripheral speed 9.5 times as great as the peripheral speed of thepulleys 29, 3| and 32. The tow is stretched in this manner to increaseits length to about 9.5 times its original length while its total denieris reduced to about 1650. Two ends of the stretched tow are passedsimultaneously to the breaker-draft rollers, which are spaced about sixinches apart and are operated with the second set of rollers 5| and 52having a peripheral speed about 1.6 times the speed of the first set ofrollers 41, 48 and 49. The continuous filaments making up the tow arebroken into fibers of staple length as they pass through thebreaker-draft rollers converting the tow into a sliver. From thebreaker-draft rollers, the tow passes directly to the fly frame whichtwists and draws the sliver into a roving having a total denier of about2100 and approximately 0.25 turn per inch, and winds the roving onto apackage. The roving is then unwound lfrom the package and is saponifiedby being subjected for two minutes to the action of a saponifying bathmaintained at a temperature of 98 C. and having a concentration of 3%sodium hydroxide and 8% sodium acetate. The roving is then washed forone minute and is finally dried. During the saponification, the fiberslose a portion of their weight with the result that the dried roving hasa total denier of about 1300. Two ends of the roving are then doubledand converted to a yarn on a conventional ring spinning frame in whichthe spindles rotate at a speed of about 7500 R. P. M., operated at adraft ratio of about 30 and employing 2 inch rings. The yarn exhibits atenacity between about 4 to 5 grams per denier and an unusually highdimensional stability.

It is to be understood that the foregoing detailed description is givenmerely by way of iilustration and that many variations may be madetherein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by LettersPatent is:

1. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of stretched continuousfilaments having a basis of an organic acid ester of cellulose, thesteps which comprise breakerdrafting said tow-while the filaments are inan unplasticized state to convert the continuous filaments into fibersof staple length, and saponifying the fibers to convert the organic acidester of cellulose to regenerated cellulose.

2. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of stretched continuousfilaments having a basis of an organic acid ester of cellulose, thesteps which comprise converting said tow to a sliver by breaker-draftingsaid tow while the filaments are in an unplasticized state to convertthe continuous filaments into fibers of staple length, imparting a twistto the sliver to convert the same into a roving, and saponilying saidroving to convert the organic acid ester of cellulose to regeneratedcellulose.

3. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of stretched continuousfilaments having a basis of an organic acid ester of cellulose, thesteps which comprise converting said tow to a sliver by breaker-draftingsaid tow while the filaments are in an unplasticized state to convertthe continuous filaments into fibers of staple length, imparting a twistof between about 0.25 and 1 turn per inch to the sliver to convert thesame into a roving, and saponifying said roving to convert the organicacid ester of cellulose to regenerated cellulose.

4. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of an organic acid ester of cellulose, the steps whichcomprise stretching said tow, breaker-drafting said tow while thefilaments are in an unplasticized state to convert the continuousfilaments into fibers of staple length, and saponifying the fibers toconvert the organic acid ester of cellulose to regenerated cellulose.

5. In a process for producing spun yarns and the like oi high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of an organic acid ester of cellulose, the steps whichcomprise stretching said tow while the filaments are in a plasticizedstate, breaker-drafting said tow while the filaments are in anunplasticized state to convert the continuous filaments into fibers ofstaple length, and saponifying the fibers to convert the organic acidester of cellulose to regenerated cellulose.

6. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of an organic acid ester of cellulose, the steps whichcomprise stretching said tow while the filaments are in a plasticizedstate, converting said tow to a sliver by breaker-drafting said towwhile the filaments are in an unplasticized state to convert thecontinuous filaments into fibers of staple length, imparting a twist tothe sliver to convert the same into a roving, and saponifying saidroving to convert the organic acid ester of cellulose to regeneratedcellulose.

'7. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of an organic acid ester of cellulose, the steps whichcomprise plasticizing the filaments in said tow, stretching said towwhile the filaments are in a plasticized state, returning the filamentsin said tow to an unplasticized state, converting said tow to a sliverby breakerdrafting said tow while the filaments are in an unplasticizedstate to convert the continuous filaments into fibers of staple lengthwithout interrupting the continuity of the tow, imparting a twist to thesliver to convert the same into a roving, and saponifying said roving toconvert the organic acid ester of cellulose to regenerated cellulose.

8. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of an organic acid ester of cellulose, the steps whichcomprise plasticizing the filaments in said tow by subjecting saidfilaments to the action of steam or hot water, stretching said tow whilethe filaments are in a plasticized state, returning the filaments insaid tow to an unplasticized state by cooling said filaments, convertingsaid tow to a sliver by breaker-drafting said tow while the filamentsare in an unplasticized state to convert the continuous filaments intofibers of staple length without interrupting the continuity of the tow,imparting a twist to the sliver to convert the same into a roving, andsaponifying said roving to convert the organic acid ester of celluloseto regenerated cellulose.

9. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of an organic acid ester of cellulose, the steps whichcomprise plasticizing the filaments in said tow, stretchin said towwhile the filaments are in a plasticized state, returning the filamentsin said tow to the unplasticized state, converting said tow to a sliverby breakerdrafting said tow while the filaments are in an unplasticizedstate to convert the continuous filaments into fibers of staple lengthwithout interrupting the continuity of the tow, imparting a twist to anddrafting the sliver to convert the same into a roving, and saponifyingsaid roving to convert the organic acid ester of cellulose toregenerated cellulose.

10. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of stretched continuousfilaments having a basis of cellulose acetate, the steps which compriseconverting said tow to a sliver by breaker-drafting said tow while thefilaments are in an unplasticized state to convert the continuousfilaments into fibers of staple length, and saponifying the fibers toconvert the cellulose acetate to regenerated cellulose.

11. In a process for producing spun yarns and the like of high-tenacityregenerated. cellulose staple fibers from a tow of stretched continuousfilaments having a basis of cellulose acetate, the steps which compriseconverting said tow to a sliver by breaker-draiting said tow While thefilaments are in an unplasticized state to convert the continuousfilaments into fibers of staple length, imparting a twist to the sliverto convert the same into a roving, and saponifying said roving toconvert the cellulose acetate to regenerated cellulose.

12. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of cellulose acetate, the steps which comprise stretchingsaid tow while the filaments are in a plasticized state, converting saidtow to a sliver by breaker-drafting said tow while the filaments are inan unplasticized state to convert the continuous filaments into fibersof staple length, imparting a twist to the sliver to convert the sameinto a roving, and saponifying said roving to convert the celluloseacetate to regenerated cellulose.

13. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of cellulose acetate, the steps which compriseplasticizing the filaments in said tow, stretching said tow while thefilaments are in a plasticized state, returning the filaments in saidtow to an unplasticized state, converting said tow to a sliver bybreaker-drafting said tow while the filaments are in an unplasticiz edstate to convert the continuous filaments into fibers of staple lengthwithout interrupting the continuity of the tow, imparting a twist to thesliver to convert the same into a roving, and saponifying said roving toconvert the cellulose acetate to regenerated cellulose.

14. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous: filamentshaving a basis of cellulose acetate, the steps which compriseplasticizing the filaments in said tow by subjecting said filaments tothe action of steam or hot Water, stretching said tow while thefilaments are in a plasticized state, returning the filaments in saidtow to an unplasticized state by cooling said filaments, converting saidtow to a sliver by breaker-drafting said. tow while the filaments are inan unplasticized state to convert the continuous filaments into fibersof staple length without interrupting the continuity of the tow,imparting a twist to the sliver to convert the same into a roving, andsaponifying said roving to convert the cellulose acetate to regeneratedcellulose.

15. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of continuous filamentshaving a basis of cellulose acetate, the steps which compriseplasticizing the filaments in said tow, stretching said tow while thefilaments are in a plasticized state, returning the filaments in saidtow to an unplasticized state, converting said tow to a sliver bybreaker-drafting said tow while menses the filaments are in anunplasticized state to convert the continuous filaments into fibers ofstaple length without interrupting the continuity of the tow, impartinga twist to and drafting the sliver to convert the same into a roving,and saponitying said roving to convert the cellulose acetate toregenerated cellulose.

16. In a process 'for producing spun yarns and the like of high-tenacityregenerated cellulose staple fibers from a tow of between about 100 and15,000 continuous filaments having a basis of an organic acid ester ofcellulose and a total denier of between about 10,000 and 150,000, thesteps which comprise stretching said tow to increase the length of thefilaments in said tow by between about 150 to 2000% based on theiroriginal length while the filaments in said tow are in a plasticizedstate, converting said tow to a sliver by breaker-drafting said towwhile the filaments are in an unplasticized state to convert thecontinuous filaments into fibers having a length of between about 3 and8 inches, imparting a twist of between about 0.25 and 1 turn per inch tothe sliver to convert the same into a roving, and saponifying saidroving. to convert the organic acid ester of cellulose to regeneratedeellulose.

17. In a process for producing spun yarns and the like of high-tenacityregenerated cellulose 12 the filaments in said tow are in a plasticizedstate, converting said tow to a sliver by breakerdratting said tow whilethe filaments are in an unplasticized state to convert the continuousfilaments into fibers having a length of between about 3 and 8 inches,imparting a twist of between about 0.25 and 1 turn per inch to thesliver to convert the same into a roving, and saponiiying said roving toconvert the cellulose acetate to regenerated cellulose.

WILLIAM WHITEHEAD. JOHN B. STEIDING. LEO B. BROWN. WILLIAM L. ROONEY.

REFERENCES CITED The following references are or record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,003,400 Taylor et a1. June 4,1935 2,053,766 Dreyfus Sept. 8, 1936 2,067,062 Gswald Jan. 5, 19372,091,967 Dreyfus Sept. 7, 1937 2,098,981 Sowter Nov. 16, 1937 2,127,283Beek et a1. Aug. 16, 1939 2,211,920 Aiibert.. Aug. 20, 1940 2,427,955Furness Sept. 23, 1947 2,432,355 tt Dec. 9, 1947 EDGE? PA 5- NumberCountry Date 635,987 Great Britain Mar. 8, 1935 467,251

Great Britain Sept. 9, 1935

1. IN A PROCESS FOR PRODUCING SPUN YARNS AND THE LIKE OF HIGH-TENACITY REGENERATED CELLULOSE STAPLE FIBERS FROM A TOW OF STRETCHED CONTINUOUS FILAMENTS HAVING A BASIS OF AN ORGANIC ACID ESTER OF CELLULOSE, THE STEPS WHICH COMPRISE BREAKERDRAFTING SAID TOW WHILE THE FILAMENTS ARE IN AN UNPLASTICIZER STATE TO CONVERT THE CONTINUOUS FILAMENTS INTO FIBERS OF STAPLE LENGTH, AND SAPONIFYING THE FIBERS TO CONVERT THE ORGANIC ACID ESTER OF CELLULOSE TO REGENERATED CELLULOSE. 